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monkeyman
Joined: 05 Jun 2008
Posts: 18
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| RS232 timeout error with fgetc() function |
 Posted: Fri Sep 23, 2011 8:11 am |
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i have 2 Rs232 on my project, one harware and one software.
| Code: |
#use rs232(baud="baud rate", xmit=PIN_"w", rcv=PIN_"x" , stream=hard)
#use rs232(baud="baud rate", xmit=PIN_"y", rcv=PIN_"z" , timeout=1000, stream=soft)
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I want to know on RS232 stream=soft if i can check timeout error with fgetc(soft) function :
| Code: |
answer=fgetc(soft);
if(answer==0)
{
...
"error timeout treatment"
...
}
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thanks |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Fri Sep 23, 2011 8:20 am |
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try the
kbhit() built in function - it works with streams as an option too
poll kbbit() UNTIL till true - then ONLY do a single getc() WHILE (true==kbhit())
no time wasted - no hanging of your program on a dead serial channel
if you define an edge interruptible portB RX pin - you can do a very nice job of making your own bkbhit function too - based on interrupt captured chars from YOUR RX buffer - i will post a program that demos a software based
rs232 hack i did some time ago that implements this next
-------
read all about it in the RS232 overview section of the CCS manual
Last edited by asmboy on Fri Sep 23, 2011 9:58 am; edited 2 times in total |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Fri Sep 23, 2011 8:34 am |
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| Code: |
// using 4.9152mhz clock for zero err baud division
// max safe baud rate 9600
// with 9.83 mhz 19200 MY CTL PACKET IS ONLY 12 CHARS LONG
// SO USING BUFFER OF 16 in this example
// timer0 used to be sure incoming packets are complete
// before attempting reply - to avoid char distortion and loss
// due to interrupt - T
#include <16f818.h>
#include <stdlib.h>
#Fuses HS,NOWDT,PUT, MCLR,BROWNOUT,NOLVP,NOCPD,WRT,NODEBUG,CCPB3,NOPROTECT
#use delay( clock=4915200)
#use rs232(baud=9600 , xmit=PIN_B1, rcv=PIN_B0, sample_early)
#use fast_io(A)
#use fast_io(B)
#bit T0IF = 0x0B.2 // flag in INTCON reg
//
#define BUFFER_SIZE 16
BYTE RISR_out; // global background newchar from ISR BACKGND buffer
BYTE buffer[BUFFER_SIZE];
BYTE next_in = 0;
BYTE next_out = 0;
#define bkbhit (next_in!=next_out)
void bgetc(void) {
RISR_out=buffer[next_out]; // NOTE : using GLObal return char variable
++next_out;
if (BUFFER_SIZE==next_out) next_out=0;
}
void SIsr_INIT(void){
clear_interrupt( int_ext );
EXT_INT_EDGE(H_TO_L);
enable_interrupts(int_ext);
enable_interrupts(global);
}
#int_ext
void serial_isr() {
int t;
buffer[next_in]=getc(); t=next_in;
++next_in
if (BUFFER_SIZE==next_in) next_in=0;
if(next_in==next_out) next_in=t; // Buffer full !!
}
//***********************************
void InitHDW ( void ) {
//***********************************
setup_oscillator ( 4915200 ); //
output_a (0); output_b (0); set_tris_a (0xFF); // - all INPUT
setup_timer_0( RTCC_DIV_64); // set for rollovers ~12 ms holdoff later
set_tris_b (0b00000001); output_b (0);
}
//===================================
void main()
{
char v; char t; unsigned int8 a; unsigned int8 b;
InitHDW();
SIsr_INIT();
printf ("*Hello*\r"); // just check output
delay_ms(12000); // delay to let me send a packet in
while (1) { // now get AND send at same time
a=next_in; // get mark of buffer position
T0IF = 0;
b=3; // clear t0if and do 3x12 MS +/-
while(b){ // TIMER0 just rolls over endlessly
if ( T0IF ) { // not using INTS - just watching timer
--b; T0IF=0;
if (!b && a==next_in ){ // unload IF no NU chars R caught
// your (safer) xmit routine here
while (bkbhit){ bgetc(); putc(RISR_out);} //simple test
} // Implied ELSE - keep waiting
} // END : IF t0if
} // END : WHILE B
} // END : while 1
}
//******
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